Voter turnout was 13 percent, with more than one in five of those votes cast by absentee ballot.

Ron Paul ranked third in Grand Rapids with 12.9 percent of the vote. Newt Gingrich, with 4.4 percent, was fourth.

Elsewhere in Kent County, Romney on Tuesday outpolled fellow Republicans in only three municipalities: Cannon Township, East Grand Rapids and Kentwood. With most of the county's precints counted, Romney had polled just more than 40 percent of the vote.

In Grand Rapids, Romney topped Santorum only in the city’s Third Ward, which is predominantly Democratic.

Santorum also topped the GOP field in other area counties, getting more than 50 percent of the vote in Allegan and Newaygo counties. He also has more than half the vote in Ottawa County, where not all votes have been counted yet.

Romney polled 36.2 percent in Muskegon County, 35 percent in Ionia County and 34 percent in Barry County. But he slipped below 30 percent in Newaygo County.